diff --git a/Misc/NEWS b/Misc/NEWS
index 260538b7402..b41fd8d79f5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -991,6 +991,11 @@ Tools/Demos
 - Issue #28102: The zipfile module CLI now prints usage to stderr.
   Patch by Stephen J. Turnbull.
 
+Build
+-----
+
+- bpo-29643: Fix ``--enable-optimization`` didn't work.
+
 Tests
 -----
 
diff --git a/configure b/configure
index 26b4a052711..87504d20683 100755
--- a/configure
+++ b/configure
@@ -6521,7 +6521,7 @@ $as_echo_n "checking for --enable-optimizations... " >&6; }
 # Check whether --enable-optimizations was given.
 if test "${enable_optimizations+set}" = set; then :
   enableval=$enable_optimizations;
-if test "$withval" != no
+if test "$enableval" != no
 then
   Py_OPT='true'
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
diff --git a/configure.ac b/configure.ac
index 8ab1c03ed89..f9bd92ce3da 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1274,7 +1274,7 @@ Py_OPT='false'
 AC_MSG_CHECKING(for --enable-optimizations)
 AC_ARG_ENABLE(optimizations, AS_HELP_STRING([--enable-optimizations], [Enable expensive optimizations (PGO, etc).  Disabled by default.]),
 [
-if test "$withval" != no
+if test "$enableval" != no
 then
   Py_OPT='true'
   AC_MSG_RESULT(yes);